Treatment of artificial filaments, fibers, and the like



Sept. 28, 1937. H. DREYFUS 2,094,099

TREATMENT OF ARTIFICIAL FILAMENTS, FIBERS, AND THE LIKE Filed April 26, 1935 PIC-T 1- HENRY DREYFUS INVENTOR Patented Sept. 28, 1937 ATENT OFFICE Henry Dreyfus, London, England Application April 26, 1933, Serial No. 668,071 In Great Britain May 11, 1932 13 Claims.

Ihis invention relates to improvements in the treatment of filaments, fibers and the like, and is more particularly concerned with processes in which artificial filaments, yarns, threads, foils, 5. films and the like, especially those containing cellulose acetate or other cellulose esters or ethers, are treated with solutions of softening agents, which may be solvents, swelling agents or plasticizers, and especially in such high concentration that a normal Washing ofi of the softening agent is accompanied by deleterious action on the filaments themselves. Usually the pur pose of applying the solvents or other softening agents in such concentration is to render possible the application of a considerable stretch to the materials, though they are also employed for other purposes, e. g. shrinking.

In U. S. Patent No. 1,709,470, processes are described for the treatment of cellulose acetate filaments or the like which are deleteriously afiected by the action of hot aqueous media, the said treatment consisting in stretching the filaments until they are resistance to the action of such media. The stretching process may be assisted by treating the materials before or during the stretching operation with suitable solvents or swelling agents, such as aqueous acetone, aqueous alcohol, glycerine or formaldehyde. In U. S. application S. No. 378,684 filed 16th July, 1929 I have described how such stretching processes of filaments, yarns or the like of cellulose acetate or other cellulose esters or ethers may be applied to the travelling filaments, as for example in a bobbin to bobbin operation or in any other rewinding operation or in an operation conducted continuously with the manufacture of the filaments. Again in my U. S. application S. No. 403,140 filed 28th October, 1929, of which the present application is a continuation-in-part, I have described the advantages which accrue from treating such materials with solvents in high concentration, the purpose of the treatment being either to improve the extension, or, if a stretching process is applied in addition to the treatment with solvents, to increase the tensile strength. Again in U. S. applications S. Nos. 402,785 filed 26th October, 1929, 418,414 filed 3rd January, 1930, 437,423 filed 20th March, 1930, 589,428 filed 28th January, 1932, 601,043 filed 24th March, 1932 and 607,668 filed 26th April, 1932 processes are described in which solutions of cellulose acetate or other cellulose esters or ethers are spun into filaments or the like by wet spinning methods, the coagulating medium consisting of or containing 55 a solvent or other softening agent for the material of .the filaments in a high concentration. In all such processes it is advisable to remove the solvent from the treated filaments very carefully in order to avoid decrease in tenacity, and still more important, decrease in the lustre of the materials. As described in a number of the said specifications the solvent may be removed by treating the filaments with the same or a different solvent in a lower concentration or by treating the filaments with the solvent in a continually decreasing concentration.

According to the present invention, in processes in which the artificial filaments, threads, yarns, ribbons and similar materials are treated with solutions containing solvents or other softening agents, the concentration and/0r volume of such solution is changed during the treatment or at the end of such treatment or of a stage thereof, and the materials subjected to further treatment with the solution under such changed conditions.

The most important application of the present invention is in relation to the washing of artificial materials which have been treated with solutions of softening agents, particularly of high concentrations, as for example inthe stretching or coagulating processes referred to above. In such processes the concentration of the solutions will in general be reduced either in a single stage or in a number of stages or continuously by the introduction of suitable diluent. Such diluent may be added to the whole bulk of softening solution so that the volume of such solution is increased, or to a relatively large proportion of such solution, the total volume of the solution being increased or maintained constant or reduced, as is desired. Increase of the volume of solution may in some cases be desirable. Thus, in stretching processes, on account of the stretching of the materials, their velocity increases during the process, and by increasing the volume of softening liquid the rate of flow of such liquid may be increased and the relative velocities of the materials and the liquid may be maintained constant or adjusted as desired. Preferably, however, and particularly in stretching processes, the main bulk of the softening liquid is returned and employed again in the first treatment bath, and only a small proportion is altered as regards concentration and/or volume and employed for the further treatment of the materials, for example for Washing them off. As stated above, preferably the concentration of such portion is reduced, either at one stage or in several stages or continuously.

The further treatment with the softening medium or portion thereof may be carried out in the same bath as the first treatment or in a separate compartment thereof or in a separate vessel into which the materials are passed. Thus the further treatment bath may form a part of the coagulating bath or of the treating bath in a stretching process and may be separated therefrom by any suitable partition. The best results are obtained according to the present invention by having a progressive flow of the softening medium from one end of the coagulating or treating bath to the other, the compartment in which the washing operation is carried out being, of course, formed at the end towards which the softening medium flows. The filaments, yarns or the like are preferably carried into the washing compartment or vessel without leaving the softening medium at any stage. Thus, for instance, they may be passed over or under a suitable partition arranged in the actual softening bath as already described. For this purpose the partition may be furnished with a suitable roller, fixed or rotatable, or with any other smooth surface over which or under which the filaments, yarns or the like may be carried without damage thereto. When the filaments, yarns etc., are required to pass under a partition, the latter may be placed in position after the materials are threaded up for the stretching operation.

Preferably, as stated above, when the softening medium in the coagulating bath or in the treatment bath for a stretching operation is allowed to flow progressively towards the compartment in which washing is carried out, only a proportion of the solvent medium or other softening agent carried therethrough is allowed to enter the washing compartment or vessel.

The proportion of solvent or other softening liquid thus leaving the softening bath and being carried into the washing bath may be adjusted as desired. Thus, for instance, it may be proportioned so as to give a definite concentration of softening agent in the washing bath, but preferably it is so proportioned that the amount of softening medium leaving the softening bath is that which requires to be reconditioned for use in the softening bath. Thus, for instance, if in a wet spinning process or in a softening bath for a stretching process a proportion of onehundredth of the total liquor passing through is withdrawn from the bath and reconditioned, then according to the present invention such a proportion may be carried from the softening bath into the washing compartment or vessel. Where a definite proportion of the total solvent or other softening liquid is allowed to fiow from the swelling bath to the washing bath, the concentration of the latter may be adjusted by suitable regulation of the inflow of diluent.

It is advantageous according to the present invention to arrange in the washing compartment or other further treatment vessel a continuously decreasing concentration of softening agent. This may be achieved by arranging a suitable flow of non-solvent diluent into such compartment or vessel. vent diluent may be arranged at different points in this compartment or vessel so as gradually to dilute the softening medium fiowing from the softening compartment. Thus, for example, the filaments, yarns or the like proceeding from the softening bath may be carried under a suitable partition into the compartment in which the washing is effected. Upon entering this com- For example, inlets for the non-sol-' partment the filaments are still subjected to the same concentration of softening agent as that existing in the softening bath. At a suitable level or point in the compartment, preferably near the partition, non-solvent diluent is run in so as to decrease the said concentration, and at different levels or different points along the length of the compartment in which washing takes place, further diluent may be added so as still further to decrease the concentration of the softening agent in contact with the filaments. The diluent thus added to the softening liquid in the washing compartment is preferably the same as that used to dilute the softening agent to the requisite concentration in the softening bath. The diluent may, if desired, include salts, sugars or other substances adapted to minimize or prevent deleterious action upon the materials of a decrease in the concentration of solvent or other softening agent. Such substances are more especially of value when water is employed as the diluent.

The remainder of the solvent or other softening liquid flowing through the softening bath may be drawn off, as for example by a suitable pipe preferably provided with a valve, or by a suitable weir or overflow, and may be returned to the other end of the stretching or coagulating bath. Similarly the diluted solvent flowing through the washing compartment may be suitably drawn off, as for example by a valved pipe or by a weir or overflow.

Any suitable solvent or strong swelling agent or other softening agent may be used in the stretching or other treatment bath or in the coagulating bath in the case of wet spinning for the purpose of the present invention. Examples of such solvents or other softening agents are:-

aqueous solutions of thiocyanates, such as those of the alkalics, ammonium and alkaline earths, aqueous solutions of zinc chloride, acetic acid, formic acid, lactic acid, diacetone alcohol, acetone and the like; the ethers, esters or etheresters of olefine glycols and polyolefine glycols or of other polyhydric alcohols, for instance the monoand di-methyl and ethyl ethers of ethylene glycol, the mono-methyl and ethyl ethers of propylene glycol, and the mono-ethyl ether of diethylene glycol, dioxane, methylene ethylene dioxide and their homologues and substitution products, glycol mono-acetate, methyl glycol mono-acetate, mono-, di-, and tri-acetins, etc; phenols, formaldehyde, acetaldehyde, dichlorethylene, methylene chloride and the like, or mixtures of these, or solvent mixtures.

The stretch imparted to the filaments or other products in the softening bath or coagulating bath may be applied in a single stage or in a plurality of stages as described in U. S. applications S. Nos. 573,424 filed 6th November, 1931 and 589,428. It is preferable that the filaments or other products should retain plasticity between stages of stretching. The whole process may be carried outwith the filaments, yarns, etc. in warp formation as described in U. S. application S. No. 602,844 filed 2nd April, 1932. It is not essential that the application of the stretching force should precede entry of the filaments, yarns or the like into the washing bath since in this bath the materials may become more or less hardened so that they are capable of transmitting a stretching force applied in the washing bath or subsequent thereto back to the softened portion of the materials.

Though particularly addressed to the treatment of cellulose acetate materials, the present invention is applicable to the treatment of materials made of or containingany other cellulose ester or ether, as for example cellulose formate, celluose propionate, cellulose butyrate, and esters containing higher fatty acid radicles, e. g. cellulose laurate or stearate, or mixed esters or cellulose nitro-acetate, or ethyl, butyl, or benzyl cellulose or other cellulose ethers, or mixed cellulose ethers or mixed cellulose ether-esters, e. g. ethyl cellulose acetate and oxyethyl cellulose acetate. Such cellulose esters or ethers may have any desired viscosity characteristics. For example, in the case of cellulose acetate an ester may be used having viscosity characteristics of about 10, or up to 20, or even up to 50 to 100 or more, such viscosity figures being calculated as the rate of flow of a 6% solution of the cellulose acetate in acetone as compared with the rate of fiow of glycerine taken as 100. Moreover, other artificial materials, e. g. regenerated cellulose materials such as are obtained by the viscose, cuprammonium and nitrocellulose processes, may also be treated by the processes and apparatus of the present invention.

Examples of apparatus which may be employed according to the present invention are shown in the accompanying drawing, but it is to be clearly understood that the invention is in no way limited thereto:

Figure 1 represents a plan view, Figure 2 a side view and Figure 3 a detail of a suitable form of apparatus for the stretching of artificial threads and the like in warp formation. It comprises a vessel 1 into which a warp of threads 8, supplied, of example, from a creel of bobbins, is introduced by means of a feed roller 9 from which they pass under a guide II. The individual threads are kept apart by means of the reed 10. At a suitable point in the bath is provided a partition l2 to which is fixed at the bottom a perforated pipe l3 through which softening medium is withdrawn and returnedby means of a pipe I4, a pump I9 and a pipe 20 to the top of the bath where it is re-introduced. The height of the partition I2 is preferably about the same as that of the guide ll above the bottom of the bath so that the top, preferably rounded and smooth, may act as a support for the warp of threads. Diluent is gradually introduced into the vessel by means of the perforated pipe IS, the rate of flow being controlled by the valve l5. On reaching the further end of the bath the threads pass through a reed I1 and under a draw-roller l8 rotated at a suitable speed so as to stretch them to the desired extent, and then through washing and drying apparatus, after which they are wound as desired. An outlet pipe 2| fitted with a valve (not shown) is provided at the end of the bath through which the liquid is withdrawn.

Figure 4 is a plan view, Figure 5 is a side view and Figure 6 is a section across the line A--A of a wet spinning apparatus according to the invention. In the illustrations '24 represents a candle filter connected to a spinning jet 23 from which a bundle of filaments 25 is extruded into a vessel 22. Coagulating medium is introduced into the bath by means of the pipe 35. The filament bundle passes along the bath under a guide 29 and round a draw-roller 3| to a guide 34 from which it passes to a funnel 32 and spinning pct 33 in which it is twisted and wound. At a suitable point along the vessel the side 21 is cut away and a channel 26 is formed so that the liquid in the bath is maintained at a constant level, the

excess being drawn 01f by means of the channel and through the outlet 30. A pipe 28 which is perforated along its length is provided through which a diluent is introduced into the bath. In this manner a portion of the coagulating medium is continuously withdrawn during the later stages of the travel of the materials through the bath and simltaneously diluent is continuously introduced.

The following examples aregiven in order to illustrate the invention, but it is to be clearly understood that they do not limit it in any way:

Example 1 A number of cellulose acetate threads are unwound from a creel of bobbins and are passed at a rate of 5-7 metres per minute in the form of a warp over a roller into a stretching apparatus such as is illustrated in Figures l-3 which contains a 45% solution of dioxane. The individual filaments are prevented from touching each other by means of a reed. The length of the vessel is about 100 feet and at, a point about -90 feet along the bath a large proportion of dioxane solution, e. g. -95%, is withdrawn and returned to the top of the bath by means of the pump l9 and the pipe 2!]. Water is introduced by means of the pipe I6, and the liquid is withdrawn by means of the pipe 2!. The rates .of introduction of diluent and of withdrawal through the pipe 2! are regulated so that the dioxane concentration of the liquid flowing out is about 20-25%. At the end of the bath the filaments are passed round a stretching roller which has a circumferential velocity of about 4 to 5 times that of the feed roller, so that a stretch of about 400 or 500% is produced, and are then led to washing, drying and winding apparatus.

Example 2 A 25% solution of cellulose acetate is extruded into a coagulating bath consisting of a 55% solution of diacetone alcohol in an apparatus such as is illustrated in Figures 4-6. The rates of introduction of diluent through the pipe 28 and of withdrawal through the outlet 30 are regulated so that the concentration of total solvent in the outflowing liquid is 15-20%. The coagulated threads pass under the guide to the draw-roller and thence to the spinning pot, in which they may be further washed if desired.

What I claim and desire to secure by Letters Patent is:

1. In a process for the manufacture of artificial filaments, threads, yarns, films, foils and the like wherein the materials are treated during the course of their travel from one point to another with a moving body of liquid containing a softening agent for the materials, the steps of reducing the concentration of the softening agent in at least a portion of such liquid medium and immediately subjecting the materials to a further treatment with the medium thus obtained as a part of the same operation.

2. In a process for the manufacture of artificial filaments, threads, yarns, films, foils and the like wherein the materials are treated during the course of their travel from one point to another with a moving body of liquid containing a softening agent for the materials, the steps of reducing the concentration of the softening agent in at least a portion of such liquid medium, said reduction being effected gradually over at least a portion of the path of the materials, and subjecting the materials to a further treatment with the medium thus obtained.

3. Process for the manufacture of artificial filaments, threads, yarns, films, foils and the like, which comprises extruding a solution of an organic derivative of cellulose into a moving c0- agulating medium containing a relatively high concentration of softening agent therefor, subjecting the materials to a stretching operation and washing them in the same bath with a portion of the coagulating medium diluted to a suitable concentration.

4. Process for the manufacture of artificial filaments, threads, yarns, films, foils and the like, which comprises extruding a solution of an organic derivative of cellulose into a moving coagulating medium containing a relatively high concentration of softening agent therefor, subjecting the materials to a stretching operation and washing them with a portion of the coagulating medium diluted to a suitable concentration, the dilution of the coagulating medium being effected gradually over at least a portion of the path of the materials.

5. Process for the manufacture of artificial filaments, threads, yarns, films, foils and the like containing an organic derivative of cellulose, which comprises treating the materials during the course of their travel from one point to another with a moving body of liquid containing a softening agent for the materials, subjecting the materials to a stretching operation and washing them in the same bath with a portion of the liquid medium diluted to a suitable concentration.

6. Process for the manufacture of artificial filaments, threads, yarns, films, foils and the like containing an organic derivative of cellulose, which comprises treating the materials during the course of their travel from one point to another with a moving body of liquid containing a softening agent for the materials, subjecting the materials to a stretching operation and washing them with a portion of the liquid medium diluted to a suitable concentration, the dilution of the liquid medium being effected gradually over at least a portion of the path of the materials.

'7. Process for the manufacture of artificial threads and like materials containing an organic derivative of cellulose, which comprises treating a number of like materials in warp formation during their travel from one point to another with a moving body of liquid containing a softening agent for the materials, subjecting them in the same bath to a stretching operation and washing them with a portion of the softening medium diluted to a suitable concentration.

8. Process for the manufacture of artificial threads and the like containing cellulose acetate, which comprises treating a number of like materials in warp formation during their travel from one point to another with a moving body of liquid containing a softening agent for the materials, subjecting them to a stretching operation and immediately washing them as a part of the same operation with a portion of the softening medium diluted to a suitable concentration.

9. Process for the manufacture of artificial filaments, threads, yarns, films, foils and the like, which comprises extruding a solution of cellulose acetate into a coagulating medium containing a relatively high concentration of a softening agent therefor and flowing in the direction of travel of the formed materials, subjecting the materials to a stretching operation, and immediately washing them continuously with their production and as a part of the same operation with a portion of the coagulating medium duluted to a suitable concentration.

10. Process for the manufacture of artificial filaments, threads, yarns, films, foils and the like containing cellulose acetate, which comprises treating the materials during their travel from one point to another with a solution of a suitable softening agent therefor, flowing in the direction of travel of the materials, subjecting them to a stretching operation, and washing them in the same bath with a portion of the softening medium diluted to a suitable concentration.

11. Process for the manufacture of artificial filaments, threads, yarns, films, foils and the like containing cellulose acetate, which comprises treating the materials during their travel from one point to another with a solution of a suitable softening agent therefor, flowing in the direction of travel of the materials, subjecting 'them to a stretching operation, and washing them with a portion of the softening medium diluted to a suitable concentration, the dilution of the softening medium being effected gradually over at least a portion of the path of the materials.

12. In apparatus for the treatment of artificial filaments, threads, yarns, foils and the like, a vessel adapted to contain a liquid medium, means for causing a flow of liquid medium through such vessel, means for withdrawing liquid medium along at least a substantial portion of the length of the vessel, means for introducing further liquid medium along at least a substantial portion of the length of the vessel said portions of the length of the vessel being at least in part identical, and. means for passing the artificial materials through such vessel.

13. Apparatus according to claim 12 wherein means are provided for re-introducing into the vessel the liquid medium withdrawn from the vessel along at least a substantial portion of its length so as to produce a continuous circulation of liquid medium through a portion of such vessel.

HENRY DREYFUS.

CERTIFICATE OF CORRECTION.

Patent No. 2,091+,099., September 28, 1957.,

HENRY DBEYFUS.

It is hereby certified that errorappears in the printed specification of the above numbered patent requiring correction as follows: Page I, first column, line 25, for "resistance" read resistant; page '5, first column line 56, for the words "of example read for example; page h, first column, line 56, claim '7 strike out "in the same bath" and insert the same after them in line 57; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office. Signed and sealed this 1st day of March, A.' D. 1958.

Henry Van Arsdal'e, (Seal) Acting Commissioner of Patents. 

